The subject of this invention is an improvement for valve couplers designed to facilitate the return of locking balls to the locking position.
The invention thus concerns the type of valve coupler which comprises an outside tubular body, one end of which is provided with a means of solid coupling to a source of fluid under pressure and which accommodates a tubular element free to move axially in both directions, whereby the front end of the inner tubular element which matches the free end of the tubular body and comprises the female fitting of the coupler, accommodates the locking balls which are housed in an annular row of holes, whereby the balls are intended to be engaged in and located by an external annular groove provided for this purpose adjacent to the end of the male coupler fitting, whereby a spring acts to return this tubular element to a stable intermediate position in which the annular row of holes in which the locking balls are housed coincides in an axial plane with a radial internal rib with tapered faces provided in the tubular body in order to maintain the balls in their locking position, that is to say in a position in which they project radially inside the bore in the mobile tubular element, whereby the latter is provided with a valve towards its rear end, which is normally maintained in a closed position by means of a spring and is designed to be withdrawn to an open position by the valve of the male fitting whenever the latter is inserted in the female fitting.
It will be easily seen that in this type of coupler, any axial movement of the inside tubular element away from its stable intermediate position will tend to move the locking balls away from the rib inside the body and will allow them to move radially outwards until they are entirely clear of the bore.
With this arrangement, the male fitting can be locked in the female fitting by simply forcing it against the pressure exerted by the return spring with which the inside tubular element is provided and against the pressure exerted by the fluid supply which acts on the valve of the female fitting; conversely, simple tractive force exerted on the aforesaid return spring alone will be sufficient to uncouple it from the female fitting.
The advantage of this type of coupler lies in the fact that it can be operated with one hand.
In known couplers of this type, the inside tubular element is maintained in its stable intermediate position with the help of a return spring coiled around the tubular element itself and which is normally compressed between two opposite external and two opposite internal shoulders, whereby the latter are at the same distance from one another as the former and the latter are provided in the bore of the body, whereby the position at which the two pairs of internal and external shoulders coincide with one another coincides as well with the locking position of the balls.
In practice and on account of manufacturing constraints, at least some of the aforesaid shoulders consist of screw collars or fitted circlips which tend to raise the cost of manufacturing and assembling such couplers. Moreover, under certain conditions, and especially when the supply fluid is at a high pressure, manual coupling becomes extremely difficult or even impossible, since the inward radial force exerted on the balls by the rear ramp of the internal rib of the tubular body requires a slight forward movement of the inside tubular element and consequently, requires the male fitting to be withdrawn somewhat, and this may occur too late, since the annular groove in the male fitting will no longer be aligned with the annular row of balls.
Furthermore, if there is any residual pressure in the user line, that is to say downstream of the male fitting, this pressure will tend to shift the balls radially outwards as soon as this valve opens, and this will prevent them from falling into the groove in the male fitting.